@mixin xxoo($w, $h:400px) {
    width: $w;
    height: $h;
    @if ($w < 200px) {
        background-color: yellow;
    } @else if ($w < 400px) {
        background-color: orange;
    } @else {
        background-color: purple;
    }
}
div {
    @include xxoo(200px);
}
.box1 {
    @include xxoo(100px);
}
.box2 {
    @include xxoo(500px);
}